A time- and frequency-selective fading channel, namely, a time and frequency doubly selective channel (hereinafter referred to as “doubly selective channel”) is a hotspot of recent research, such as underwater acoustic communication, low orbit satellite communication, Digital video broadcasting (DVB), and Worldwide Interoperability for Microwave Access (WiMAX). Channels for transmission in these communication application fields are all doubly selective channels. A doubly selective fading channel has significant impact on communication quality, and how to compensate for a doubly selective channel has become a problem that needs to be urgently resolved.
To compensate for a doubly selective channel, a method in the prior art is to apply partial Fast Fourier Transform (FFT) demodulation to an Orthogonal Frequency Division Multiplexing (OFDM) system. However, because the OFDM system is subject to a fast time-varying doubly selective channel, the OFDM system is affected by inter-carrier interference that is caused by a Doppler effect. In view of this, in another existing method, it is proposed that partial FFT demodulation is applied to a hybrid carrier system, which greatly improves performance; however, due to very high complexity, the method is limited in an actual application. In yet another method, by using a property of a doubly selective channel, a banded Minimum Mean Square Error (MMSE) equalization method is applied to the OFDM system, which reduces calculation complexity, but is not very ideal in terms of bit error rate performance.